[PATCH] D103745: [dfsan] Add full fast8 support

[Andrew via Phabricator via cfe-commits]

browneee added a subscriber: kcc.
browneee added a comment.

In D103745#3094831 <https://reviews.llvm.org/D103745#3094831>, @twoh wrote:

> @gbalats @stephan.yichao.zhao Hello sorry for the late comment but I wonder what was the reason behind this change (changing taint label representation from 16-bit to 8-bit-fast only). Do we have any discussion thread from llvm-dev regarding this? Thanks!

Hi twoh,

The reasons are:

- simplify code (smaller codesize overhead)
- share more code and shadow/origin memory layout with MSan (which also has a 1:1 shadow)
- reduce memory overhead

The only disadvantage is you need 2x executions to cover the same number of taint labels, but we already need do multiple executions.

There was no discussion thread, but we discussed with @kcc internally.


Repository:
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  https://reviews.llvm.org/D103745/new/

https://reviews.llvm.org/D103745